#include<bits/stdc++.h>
using namespace std;
int a[200001];
int n,m;
int tree[200005];

void build(int index,int l,int r){
	if(l==r){
		tree[index]=a[l];
	}
	else{
		int mid=(l+r)/2;
		build(index*2,l,mid);
		build(index*2+1,mid+1,r);
		tree[index]=max(tree[index*2],tree[index*2+1]);
	}
}

int query(int index,int l,int r,int x,int y){
	if(l<=x && r<=y){
		return tree[index];
	}
	int mid=(l+r)>>1,ret=0;
	if(x<=mid){
		ret=max(query(index*2,l,mid,x,y),ret);
	}
	if(y>=mid+1){
		ret=max(ret,query(index*2+1,mid+1,r,x,y));
	}
	return ret;
}

void modify(int index,int l,int r,int x,int y){
	if(l==r){
		if(tree[index]<y) tree[index]=y;
		return ;
	}
	int mid=(l+r)>>1;
	if(x<=mid) modify(index*2,l,mid,x,y);
	else modify(index*2+1,mid+1,r,x,y);
	tree[index]=max(tree[index*2],tree[index*2+1]);
}

int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	build(1,1,n);
	char type;
	for(int i=1;i<=m;i++){
		cin>>type;
		if(type=='Q'){
			int x,y;
			cin>>x>>y;
			cout<<query(1,1,n,x,y)<<endl;
		}
		if(type=='U'){
			int x,y;
			cin>>x>>y;
			modify(1,1,n,x,y);
		}
	}
	return 0;
}